The invention relates to the injection of pulverulent materials in a blast furnace, and in particular coal.
It is well known that injecting powdered coal into a blast furnace reduces the coke consumption. The coal is introduced through an injection pipe into the hot blast coming from the Cowper stoves.
Such known injection devices comprise a hot blast tuyere issuing into the blast furnace, a nozzle fixed against said tuyere and co-axial thereto for bringing the hot blast, a branch connection produced obliquely on the nozzle and directed towards the tuyere, and an injection pipe traversing said branch connection to issue into the tuyere. In these known devices, the injection pipe is a straight pipe of which the inclination with respect to the axis of the tuyere is the same as that of the branch connection of the nozzle, namely generally 15.degree..
It has been found that this technology, though being satisfactory in many ways, presents however the disadvantage of lacking suppleness. More specifically, it is not really easy, when using said technology, to alter the position of the discharge end of the injection pipe with respect to the tuyere. Yet that position is difficult to choose since it is dependent on parameters which are in contradiction. According to some parameters, it is preferable for the injection pipe to penetrate as far as possible into the tuyere, whereas according to the others, the injection pipe should not penetrate too much. With the straight injection pipe inclined at 15.degree., it is not possible, without problems arising as to the quality of the injection, to depart from the normal position.